선박용 강재의 저주기 피로특성에 관한연구

초록

Experimental analyses were performed to examine the low cycle fatigue life of the steel for ship structure. First, both base metal and welded metal tensile tests were performed to obtain basic material properties, that is, elastic modulus, yield stress and ultimate stress about their rolling directions respectively. Basic material properties were used to evaluate the characteristics of low cycle fatigue of concerning materials. And we obtained the cyclic stress-strain curve using incremental step test and determined the cyclic strength coefficient and cyclic strain hardening exponent. Second, fatigue tests were also carried out to establish ε -N curve of low cycle area for base metal and welded joints. Static and dynamic strain for not a point but area were measured for evaluating the elasto-plastic characteristics around the notch root of the welded joint by ESPI (Electronic Speckle Pattern Interferometry) system. It was confirmed that these results could be applied to the design of low cycle fatigue for ship structural members.